I. Field of the Invention
This invention relates to a disk cache dam maintenance system which, on power failure, prevents loss of disk cache data for performing asynchronous input/output processing.
II. Description of the Related Art
A conventional disk cache structure is disclosed in "Kobayashi et al., Operating System A-VX, NEC Technical Journal, vol. 43, No. 7, pp. 105-106, NEC Corporation, 1990".
The conventional disk cache structure includes a disk cache buffer of an input/output buffer region for the disk secured in a main storage device; an asynchronous input/output control section for writing data into disks in asynchronization with the generation of a write instruction by a program, and not for immediately physically writing into disk the data which are written into the disk cache buffer in accordance with the write instruction by the user's program; and a backup memory having a battery backup device for holding the contents of the disk cache buffer.
In such a buffer memory, when the program writes data into the disk cache buffer, the same data are written into the buffer memory, and even in the event of a power failure, loss of the data is prevented since the data stored in the backup memory is reflected on the disk on re-turning ON the power supply.
However, the backup memory with the battery backup device is too expensive with less storage capacity, and such a reduced capacity causes a limited capacity of the disk cache buffer, with insufficient storage of the data. Thus, the disk cache cannot perform its function and is unable to achieve its satisfactory effects.